(1) Field of the Invention
The present invention relates to mixing-grade, quick-setting cationic aqueous bituminous emulsion-aggregate paving slurry seal mixtures. More particularly, this invention relates to said paving slurry seal mixtures formed with cationic emulsions prepared by emulsifying bitumen, such as an asphalt, in water with a cation-active emulsifier which is the product of the reaction of polyamines with certain polycarboxylic acids and containing accelerators to shorten the curing time at below 75.degree. F. The accelerators are modified nitrogen-containing tall oil fatty acids.
(2) Description of the Prior Art
Conventionally, emulsion slurry seals are formulated from (1) mineral aggregate which is a fine stone aggregate and/or mineral filler and (2) about 15% to about 25% by weight thereof of a mixing-grade, slow-setting emulsion containing from about 50% to about 75% by weight of bituminous residue (usually asphalt), with a further addition of about 5% to about 25% of water, based on the weight of the dry aggregate, to attain slurry consistency. Usually, densely-graded aggregates, such as granite screenings, limestone screenings, dolomite screenings and blast furnace slag, are combined with bituminous emulsions to produce slurry seal compositions. These aggregates range in size from anything passing all through a sieve of No. 4, and even No. 10 mesh, with from 15% to 20% passing through as fine a mesh as 200 mesh, as described in ASTM C136.
Acidified reaction products of the above described polycarboxylic acids, anhydrides, sulfonated fatty acids and epoxidized glycerides with certain polyamines are suitable emulsifiers yielding asphalt emulsions which can be mixed with fine grained aggregate to give workable aggregate/emulsion mixes.
These emulsifiers generally are disclosed in U.S. Pat. Nos. 4,447,269 to Schreuders, et al., 4,450,011 to Schilling, et al., 4,547,224 to Schilling, et al., 4,462,840 to Schilling, et al., 4,464,286 to Schilling; and 4,597,799 to Schilling.
However, the mixing performance is in many cases dependent on the source and type of the aggregate and asphalt used for emulsification. Also, climatic conditions play a major role in slurry seal application. Hot weather makes it more difficult to mix, and slurry seal will cure much faster to gain the necessary strength for rolling traffic. Low temperatures provide good mixing conditions, but the times required for slurry curing are longer than desired. Optimum formulations of slurry seal mixes provide mixing times long enough to ensure uniform mixes and, after placement on the road surface, cure fast enough to allow for quick re-opening to rolling traffic.
Accordingly, an object of this invention is to provide novel types of curing accelerators which in the presence of inorganic fillers, such as Portland cement, will reduce the time of the slurry to gain cohesive strength rapidly.
A further object of this invention is to provide a novel mixture of aggregate and bituminous emulsion.
A further object is to provide a mixture of the above character which is workable under a broad range of conditions.
Another object is to provide a mixture of cationic bituminous emulsion and aggregate whose setting time can be varied.
A particular object is to provide an aqueous bituminous emulsion fine-grained aggregate slurry mixture which deposits at a fairly rapid rate after being applied to the surface to be treated, and is usable for a longer period of time to enable application in slurry form.